Machine for generating gears



Jan. 1, 1957 L. o. CARLSEN MACHINE FOR GENERATING GEARS Filed July 14, 1954 5 Sheets-Sheet l J INVENTOR LEONARD O. CARLSEN ATTORNEY 1957 o. CARLSEN 2,775,921

MACHINE FOR GENERATING GEARS Filed July 14, 1954 3 Sheets-Sheet 2 g8 89 INVENTOR. LEONARD O. CARLSEN 60 F|G.6 BY 9 -QMJMEW ATTORNEY United States Patent'O MACHINE FOR GENERATING GEARS Leonard O. Carlsen, Rochester, N. Y., assignor to The Gleason Works, Rochester, N. Y., a corporation of New York Application July 14, 1954, Serial No. 443,256

8 Claims. (Cl. 90-3) The present invention relates to a machine for generating gears, or other toothed parts, and particularly to such machines of the type which rough cut during one generating motion and finish cut during the return motion.

In machines of this kind heretofore constructed there is a feed cam to effect a roughing in-feed of the cutting tool relative to the work just prior to or during the relative generating motion of the tool and the work. During this generating motion the Work is rough-generated close to its finished size and shape. The cam then effects a further small in-feed so that finish cutting can be ac complished during the return generating motion.

The magnitude of the roughing in-feed depends upon the tooth depth of the work, and in order to adapt the machine for a wide range of tooth depths an adjustable connection is provided between the feed cam and the slide which it operates, this connection ordinarily taking the form of an adjustable length lever. As the effective length of the lever is shortened or lengthened the stroke or depth feed of the slide during the roughing in-feed is reduced or increased. However the magnitude of the small finishing in-feed, i. e. the in-feed which immediately precedes finish cutting is also reduced or increased proportionately.

The present invention provides a means whereby the magnitude of the finishing in-feed is made independent of the roughing in-feed, so that the amount of stock removed during the finish cutting may be chosen without regard to the tooth depth of the work. According to the invention the finishing in-feed is effected by a cylinder and piston device which is actuated hydraulically in time with rotation of the feed cam. The stroke of the piston and hence the magnitude of the finishing in-feed is determined by an adjustable stop which is entirely independent of the adjustable length lever that determines the magnitude of the roughing in-feed. However the timed relationship between the two in-feeds is unchanged, remaining under the control of the feed cam.

In the accompanying drawings:

Figs. 1 and 2 are respectively a side elevation and a plan view of the machine;

Figs. 3, 4 and 5 are diagrams showing the relationship of the cutting tools to the work in difierent phases of the generating cycle;

Fig. 6 is a vertical sectional view showing the feed cam and the cylinder and piston in-feed device;

Fig. 7 is a drive diagram of the machine;

Fig. 8 is a cycle diagram showing the phase relationship between the generating motion and the roughing and finishing in-feeds; and,

Fig. 9 is a hydraulic diagram.

The machine comprises a frame 20 on which a sliding base 21 is supported for movement along ways 22. A swinging base 23 is adjustable on arcuate Ways 24 on the sliding base, and a work head 25 is adjustable horizontally on base 23 along ways 26. Rotatable in the work head is a horizontal work spindle 27 to which is clamped the gear to be cut, in this case a bevel gear.

2,775,921 Patented Jan. 1, 1957.

A tool-carrying member designated 28 is mounted for generating motion on the frame, the member in this case being a cradle mounted for rotation about a horizontal axis which intersects the axis of the work spindle. Mounted adjustably on the cradle 28 are a pair of cutter supports 29, each of which journals a spindle 31, Fig. 7, on which is mounted a cutter 32. Each cutter has radially projecting blades 33, Figs. 3-5, having side cutting edges 34 and tip cutting edges 35. The blades of each cutter extend into the inter-blade spaces of the other so that both can cut simultaneously in the same tooth space of the work gear G. It will be understood, however, that the invention is not limited to machines having this kind of cutter, for it is applicable also to machines having reciprocating or stroking tools and also to machines having other types of rotary cutters, such for example as the hobs and face mill cutters used for cutting spiral bevel and hypoid gears. Furthermore the invention is not limited to machines having a rotatable cradle, but may be applied for example to machines in which the tool-carrying member is a rectilinearly reciprocating slide, so that the tools represent a tooth of a generating rack which has a rolling generating motion relative to the work gear.

For operating the illustrated machine through its generating cycle in which the cradle and work rotate in timed relationship first in one direction and then in the opposite direction about their respective axes, the drive shown in Fig. 7 is provided. A main drive motor 36 drives feed cam 37 through a gear train comprising bevel gears 38, cutter speed change gears 39 (from which the cutters 32 are driven through the gear train shown extending to them), cycle speed change gears 41, and gearing 42. The feed cam 37 has a cam track 43 for efiecting the generating motion of the cradle and work spindle, this track being engaged by a follower roller 44 mounted on a gear segment 45. The arrangement is such that the segment is operated through one complete oscillation for each rotation of the cam. The cradle 28 is driven by the segment through a gear train comprising pinion 46, angle-of-roll change gears 47, gears 48 and hypoid reduction gears 50. The work spindle 27 is driven in time with the cradle through bevel gears 40, ratio-of-roll change gears 49, differential gears comprising side gear 51 and planet gear 52 and side gear 53, bevel gears 54 and 55, overhead telescoping shaft 56, bevel gears 57 and 58, index change gears 59, and hypoid reduction gears 61.

On cam 37 is a feed track 62 in which there is engaged a follower roller 63 carried by a lever 64 that is fulcrumed at 65 upon the machine frame. Adjustable along the lever to different distances from the fulcrum is a block 66, Figs. 6 and 7, carrying a pin 67 to which a block 68 is pivoted. Block 68 is slidable, in a direction perpendicular to the plane of Fig. 6, in a slot 69 in a cylinder 71. The cylinder contains a piston 72 whose rod 73 is screw-threaded to an adjusting nut 74, Fig. 2, carried by the sliding base 21. The cylinder itself is slidable on the frame 20 in the direction of rod 73. Once during each rotation of cam 37, after completion of the cutting of a tooth space of the work, the track 62 acts through lever 64 to withdraw the unit comprising cylinder 71, piston 72, rod 73 and sliding base 21 away from the cradle, to thereby carry the work on spindle 27 clear of the cutting tools so that the work may be indexed to bring another tooth space thereof into position for cutting.

Such indexing of the work is effected by track 75 of the cam, which through a follower roller 76 and rod 77 shifts the drive member 7 8 of a Geneva movement axially into engagement with the Geneva driven member 79. The member 78, constantly rotated by motor 36 through gearing including gears 81, then operates the driven member 79 through a fraction of a turn. This motion is transmitted through gears 82 to the planet gear 52 and, through gearing 53-61, to the work spindle 27. After such indexing is completed the cam track 75 acts to withdraw the Geneva drive member 78 from the driven member, and, through suitable lock-up means, not shown, the driven member 79 is held against rotation until the next indexing operation is begun. After each indexing operation the feed cam track 62 then acts through lever 64, and cylinder and piston device 71, 72, 73 to feed the sliding base into the cutters.

After completing a number of operating cycles sufficient to cut all the tooth spaces of the work, the machine is stopped automatically, by means, not shown, and hydraulic pressure is applied to the right face (in Fig. 6) of piston 72 to thereby withdraw the slide, further than for indexing, to a position in which the completed gear can be removed and a new gear blank chucked on the work spindle.

All of the structure so far described with reference to the drawings preceded the present invention. According to the present invention there is included in the machine a second hydraulically operated piston 83 slidable in the head 84 of cylinder 71 and constituting a movable stop which limits the advance of piston '72. The stroke of piston 83 toward piston 72 is limited by abutment of a nut 85 with a plate 86 that is secured to head 84, the nut being screw-threaded to shank 87 of piston 83. The stroke of the latter in the opposite direction is limited by abutment of its shoulder 88 with a ring 89 that is secured in head 84 by screws 91. This ring has a keyway cooperating with a key on the piston to hold the latter against turning. The length of the stroke of piston 83 is adjusted by turning the nut 85 after first loosening its lock screw 92. The length of the stroke is shown by suitable calibrations on nut 85 which are read in conjunction with a pointer 93 on plate 86. A stop pin 90 on plate 86 is engageable with the head of a screw on nut 85 to limit turning of the latter to one turn, this being SIllfiCl6Ilt for the range of stroke adjustment that is ordinarily needed.

Piston S3 is controlled by a valve 94 which is slidable in a valve housing 95, Figs. 6 and 9, mounted on the frame 20. The valve carries a roller 96 engaging in track 97 of a cam 98 which is secured to and in eiiect is a part of cam 37. The operation of the valve 94 will be understood from Fig. 9 in which there is also shown a valve 99 for controlling the piston 72, such a valve being con ventional and being operated by the valve handle 101, Figs. 1 and 2. Hydraulic pressure is supplied by a suitable system including a pump P which may be driven either by motor 36 or by an auxiliary motor, not shown.

In the position of valves 94 and 99 shown in Fig. 9, pressure from pump P is effective through passage 102, valve 94 and passage 103 to hold piston 83 in its advanced position determined by stop nut 85. Piston 72 is held in abutment with piston 83 by pressure applied to it through passage 192, valve 99 and passage 104. As shown the efiective area of piston 83 is greater than that of piston 72 so that although the unit pressures acting on the two are equal, the total pressure acting on piston 83 is greater. In this condition of the valves the exhaust or return passage 195 from valve 94 to the pump is closed by the valve, while passage 106 from cylinder 71 communicates through valve 99 with return passage 107 to the pump. This is the condition of the hydraulic system during rough cutting. Prior to finishing cutting the cam track 97 shifts valve 9 (upwardly as viewed in Fig. 9) to thereby close off passage 192 and connect passage 103 to exhaust passage 105. Consequently the pistons are moved (to the right in Figs. 6 and 9, but to the left in Figs. 1 and 2) to the limit position determined by shoulder 83. This motion advances the slide 21 so that the tools 32 cut to the greater depth desired for finish cutting.

When valve 99 is shifted to connect passages 104 and 106 respectively to return passage 107 and pressure passage 162, the piston 72 is of course moved to its limit position (to the left in Fig. 9) in which the sliding base 21 is fully withdrawn for reloading.

The shape of the cam track 97 and its phase relationship with tracks 43, 62 and 75 will be understood from the following explanation made with reference particularly to Figs. 3, 4, 5 and 8. It will be assumed that piston '72 is in its limit position (to the right in Fig. 9) determined by piston 83. When cam 37 is in its 0 position, Fig. 8, the cam track 43 has moved cradle 28 to the top of its up-roll and is ready to start the downroll. Cam track 97 holds valve 94 in the position wherein passage 193 is on exhaust. As the cam 37 rotates and track 43 causes the first part of the downroll, track 97 shifts valve 94 to put passage 103 on pressure, moving piston 83 to the position shown in Fig. 9; track 62 commences the out-feed or withdraw of the sliding base 21 that is necessary before indexing the work; and shortly thereafter indexing is effected by track 75. As the indexing is concluding, the in-feed of the sliding base by track 62 is commenced. At this time the downroll is approximately forty percent complete and the tools are in the relative position to the work gear G that is shown by broken lines 34, 35' in Fig. 3. The track 43 now causes a dwell in the downroll which extends over approximately half of the operating cycle of the machine, i. e. over about onehalf of the revolution of cam 37.

During this dwell the cam track 62 continues the infeed or advance of sliding base 21, with the result that tools and work assume the relative position reflected in Fig. 3 by the full line position of tools 33. At this time tip cutting edges 35 are spaced by a distance S, the length of stroke of piston 83, from their finish cutting position. A major portion of the stock has now been removed from the tooth space of the workpiece. A dwell in cam track 62 now becomes effective While cam track 43 resumes the downroll of the cradle, accompanied of course by rotation of the work about its axis, with the result that the tooth space is rough-generated very close to finish size. The shape of the roughed out tooth space is approximately as shown in full lines in Fig. 4, and may be compared with the finished shape shown in dotted lines, bearing in mind that the distance S is shown greatly exaggerated and in practice is usually only a matter of one or a few thousandths of an inch.

At the conclusion of the downroll the cam track 97 shifts valve 94 to put passage 103 on exhaust whereupon piston 72 moves the sliding base into its full depth, finish cutting position, wherein the tools are in the relative position indicated at 34 and 35". Simultaneously cam track 43 starts the uproll which continues until the end of the cycle, at which time the tools and work reach the relative position shown in Fig. 5. The cycle described is repeated until all the tooth spaces of the workpieces are cut.

It will be understood that the length of the roughing in-feed, from position 34, 35 to 34, 35 in Fig. 3 will depend upon the tooth depth of the workpiece and may be readily changed by adjusting block 66, Figs. 6 and 7, toward or away from fulcrum 65. The length of the finishing in-feed, S in Figs. 3, 4 and 5, is independently adjustable by means of the stroke-limiting nut 85, Figs. 6 and 9.

Having now described the preferred embodiment of my invention, and its mode of operation, what I claim is:

1. A machine for generating gears or like toothed elements, comprising a movable carrier, a tool support and a rotatable work spindle of which one is mounted on the carrier, the tool support and the work spindle being mounted for relative feed in a direction depthwise of the teeth to be cut, a generating drive train connecting the work spindle and the carrier for rolling generating motion, and means to operate said train alternately in said opposite directions, characterized by a continuously and unidirectionally rotating cam for eifecting said relative feed to bring the tool and the work spindle into nearly full depth relation, a device comprising a cylinder and piston for transmitting said feed motion from the cam, and fluid pressure means including a valve operated in time with said cam to effect relative motion of the cylinder and piston to bring the tool and Work spindle into full depth relation, whereby during the generating motion in one direction the work may be rough generated to less than full depth and during the return generating motion may be finish generated to full depth.

2. A machine according to claim 1 in which there is a means to adjust the relative stroke of the cylinder and piston, to thereby vary the amount of stock to be removed in finish cutting.

3. A machine according to claim 1 in which the valve is operated by a cam which rotates in unison with said unidirectionally rotating cam.

4. A machine according to claim 1 in which the means to operate said generating drive train alternately in opposite directions comprises a cam which rotates in unison with said unidirectionally rotating cam.

5. A machine according to claim 4 in which the valve is operated by a cam which rotates in unison with both of the aforementioned cams.

6. A machine for generating gears or like toothed elements, comprising a frame, a carrier movable relative to the frame, a tool support and a rotatable Work spindle of which one is mounted on the carrier for generating motion therewith relative to the other one thereof, means including a slide on the frame supporting the tool support and the work spindle for relative feed in a direction depthwise of a tooth space being cut, a generating drive train connecting the work spindle and the carrier for rolling generating motion, means for driving said train, and means comprising a continuously and unidirectionally rotating cam for effecting motion of the slide in predetermined timed relationship with said rolling generating motion, the last-mentioned means further comprising a cylinder reciprocable on the frame and connected to the cam for reciprocation thereby, a first piston in the cylinder connected to the slide, fluid pressure means including a valve for operating the first piston, a second piston having a limited stroke in the cylinder and arranged to limit the stroke of the first piston, and fluid pressure means including a valve operated in time with said cam for operating the second piston.

7. A machine for producing gears or like toothed parts, comprising a frame, a rotatable cutter and a rotatable Work spindle mounted on the frame, a slide on the frame supporting one of the cutter and work spindle for feed motion and return withdraw motion relative to the other in a direction depthwise of a tooth space being cut, means comprising a continuously and unidirectionally rotating cam for effecting said feed and Withdraw motions of the slide, and said means further comprising a cylinder and piston device for transmitting said motions from the cam to the slide, and fluid pressure means including a valve operated in time with said cam to effect relative motion of the cylinder and piston to thereby effect a further feed motion of the slide subsequent to the motion thereof effected by the slide.

8. A machine according to claim 7 in which the cutter is geared to the cam for rotation in time therewith and there is a means for indexing the work spindle once upon each rotation of the cam, at a time when the slide is Withdrawn, to bring a successive tooth space into cutting position.

References Cited in the file of this patent UNITED STATES PATENTS 

